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Biology 1114
Preview Material for Exam 4 - Spring 2003
During their camping trip to New Mexico, Wanda and Louise became very
interested in coyote biology - particularly what type of parasites are found in coyotes.
The wildlife biologist had mentioned that during the past few years, parasite infections
had slowed the growth rate of the coyote population in the park. They learned that one
common parasite found in coyotes as well as domestic dogs is the dog tapeworm
(Dipylidium caninum). The adult tapeworm lives in the animal's intestines where it
attaches to the intestinal wall and feeds. The tapeworm sheds segments off of its tail
end and these contain as many as 30 eggs/segment. These egg-laden segments are
shed in the animal's feces. Fleas (an ectotherm) will often feed on the eggs, which will
then hatch into larvae inside the flea. If a coyote swallows a flea that is infected with the
larval tapeworms, the larva will be liberated and grow into an adult tapeworm inside the
coyote thus completing the cycle.
A fig wasp population on Malta, a lovely and majestic island in the Mediterranean
Sea, seventy miles from Sicily, would be a population derived from the surrounding
Mainland population. The conditions (including food supply, predators, etc.) on Malta
are essentially the same as those in Sicily and much of the surrounding land. Seasonal
changes in wind patterns aid the continual migration of fig wasps back and forth between
the Maltese and Mainland populations.
Before the start of Gulf War II, Marine Chief Warrant Officer Stacy Jeambert came up
with a plan entitled Operation KFC or “Kuwaiti Field Chicken.” The plan is simple –
place individual chickens (Poultry Chemical Confirmation Devices -- PCCDs) in cages on
top of Hum-Vees (a vehicle). Soldiers then monitor the chickens and if a chicken dies,
the soldiers put on their protective suits. The chemical-warfare agents of concern are
similar to Vx and Sarin gasses, which are acetylcholinesterase inhibitors.
During Gulf War I, Jeambert obtained 5 chickens for this purpose. For Gulf War
II he “drafted” 250, which were on their way to dinner (for Kuwaiti citizens). Jeambert
built a chicken coop for them with the intention of keeping them healthy and fattening
them up.
A scientist is called in to help with the production of fat chickens. She finds that
there are two distinct forms of chickens. A NORMAL, thin type that can be fattened
through diet and lack of exercise and an overweight type (FAT) that is lethargic (does
not move much), eats constantly, and appears to store fat all the time.
Roundup is a general purpose herbicide, used for decades, that kills plants by
interfering with their ability to synthesize certain amino acids (tyrosine, phenylalanine,
tryptophan) from the carbon chains produced in chloroplasts. The active ingredient in
Roundup (glyphosate) inhibits one essential enzyme (EPSPS) in the amino acid
synthesis pathway present in plants, bacteria and fungi. If Roundup-treated organisms
cannot supply amino acids for protein synthesis, they die. Roundup does not affect
animal growth or development because animals do not synthesize these particular
amino acids, they must acquire them from food.
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In recent years, a strain of soil bacterium, Agrobacterium tumefaciens strain CP4,
was discovered to have Roundup-resistance. In other words, it is a mutant strain of a
common bacterium found in agricultural fields that synthesizes a version of EPSPS that
is not inhibited by Roundup (glyphosate). Plant molecular biologists have since inserted
the mutant CP4 version of the EPSPS gene directly into soybean chloroplasts, thus
genetically engineering a Roundup-resistant form of soybeans (Glycine max).
The advantage of Roundup-resistant soybeans or any other similarly genetically
modified crop is that a farmer can spray one herbicide to kill all weeds in the field without
hurting the soybean crop itself.
Soybeans and other legumes have developed symbiotic relationships with
Rhizobium spp. (a nitrogen-fixing bacterium). Plants provide a ready source of glucose
for the bacteria, which live in specially created root nodules, and bacteria provide a
ready source of ammonium and nitrate for the plants. Both species benefit.
In 1967 a group of researchers measured DDT (a non-degradable pesticide)
concentrations in the organisms found in an estuary on the south shore of Long Island,
New York. Some concentration levels were below the lethal thresholds, but others were
enough to interfere with reproductive success.
Organism
Summer flounder
Mud snail
Green alga
Green heron
Herring gull
DDT concentration in parts per million
1.28
0.26
0.083
3.57
18.5
Alfalfa plants are grown in fields and their shoots are used to feed chickens. An
educated farmer wants to study the effect of a fertilizer that contains phosphate on the
development of the alfalfa plants in order to increase the yield. He divides a field into
small plots and adds different amounts of the fertilizer to different plots. In a control plot
he adds no fertilizer. After a few weeks he harvests and weighs the alfalfa in each plot.
To prevent damage by insects he sprays the plants with an insecticide that concentrates
in living tissue. The insecticide is effective and kills most of the insects.